1. Field of the Invention
The present invention relates to a power amplifier module that may be applied to a global system for mobile communications (GSM) terminal, and more particularly, to a power amplifier module with a shared electrostatic discharge (ESD) protection circuit in which a high band power amplifier (PA) and a low band PA share the ESD protection circuit connected to an output terminal of a low drop output (LDO).
2. Description of the Related Art
Generally, a power amplifier for a GSM terminal is configured of a balanced power amplifier (PA) including a high band PA and a low band PA using a CMOS process technology and supplies power from an LDO of a PA controller to the high band PA and the low band PA.
In addition, each of the high band PA and the low band PA is configured of a plurality of amplifiers and is designed to have a structure able to couple and output power from each PA through a low loss substrate and a Cu 10 μm process, an integrated passive device (IPD) process, and a coupling conductive wire.
The GSM power amplifier module, according to the related art, includes a PA controller, a high band PA, a low band PA, a high band IPD power coupler, and a low band IPD power coupler that are formed on a single substrate.
As a countermeasure for protecting against ESD, the GSM power amplifier module according to the related art includes ESD protection circuits that are mounted at each output terminal of the PA controller, the high band PA, and the low band PA, such that each of the PA controller, the high band PA, and the low band PA may be protected from ESD.
However, the GSM power amplifier module according to the related art has the following problems: as the ESD protection circuits are provided at each output terminal of the PA controller, the high band PA, the low band PA to increase the size of the GSM power amplifier module and when the output signals from each of the high band PA and the low band PA are large, the output signals are limited by the ESD protection circuits and consequently, may not be output.